The present invention relates to a comber machine having a nipper head and an assembly of detaching rolls, wherein the nipper and the detaching rolls can be moved relative to each other during a combing cycle.
Modern combers go back to the pioneering designs of John William Nasmith, of about 1920. They feature oscillating nippers, reversing detaching rolls, half-lap and cleaning brushes. The separation of the fiber assembly is effected by a simultaneous back oscillation of the nippers, and a forward rotation of the detaching rolls. The detaching rolls then reverse, and in this way feed the combed tuft back again, in such a manner that the newly-combed fiber tuft can be laid on it. This is the process known as "piecing".
The quantity of comber noil which is screened out is determined by the detachment length, which is referred to as the "ecartement" (separation). By definition, the ecartement is that distance which pertains between the clamping line of the inner detaching rolls and the clamping line of the nipper knife and the cushion plate, when the oscillating nipper is closest to the clamping line of the inner detaching rolls.
The size of the ecartement determines the length of the fiber tuft which protrudes freely when the nippers are closed, and is combed through by the needle segment of the half-lap. With the fiber length distribution in the fiber tuft remaining uniform, the greater the ecartement, the more fibers are combed out. Accordingly, as the ecartement increases, so the amount of separated comber noil rises and, conversely, as the ecartement decreases the amount of noil drops. All known combers essentially control the separation of the noil due to the possibility of changing this "ecartement" value, which is determined on the machinery side, with the ecartement essentially being altered by the readjustment of the outer reversing point of the nipper movement (U.S. Pat. No. 3,479,699=Switzerland Patent 485 873). The axes of the driven detaching rolls are spatially fixed. The detaching rolls only carry out an oscillating, step-and-repeat (pilgrim step like) type of rotational movement, in order to allow for the separation of the fiber assembly and the piecing.
The adjustment of the ecartement by changing the nipper movement is, from the mechanical point of view, relatively easy to carry out in the main drive unit. It is necessary, however, for the machine to be shut down, and for the adjustment to be carried out in the hot and oily gearbox. To obtain an exact adaptation of the amount of noil, the procedure needs to be repeated frequently, resulting in considerable expenditure of time and loss of production.
In addition to the gearbox-side adjustment of the noil separation in U.S. Pat. No. 3,479,699, it is also possible to effect an adjustment of the separation by making provision for swivelling the upper, inner detaching roll about the axis of rotation of the lower detaching roll, in order at least to reduce the amount of work involved when making only minor adjustments to the ecartement.
In the wool processing industry in particular, combers are known which do not follow Nasmith' design principle (see UK-Patent 1 207 441), but rather the older design by Hellmann. In this case, the detachment movement is effected not by the nippers swinging backwards, but exclusively by a corresponding movement of the axis of the detaching rolls in forward direction. The nipper moves up and down in the rhythm of the rotation of the machine; the detaching rolls move in the rhythm of the machine both rotationally as well as in a transitional direction from rear to front and back again. As a result, per machine cycle, the axis of the detaching cylinder moves outward in one movement, and then back in again. The separation as in the case of the Nasmith machine is determined by adjusting the inside reversing point of the detaching roll oscillation.
In view of the fact that the oscillating masses are high in this type of design, large forces of inertia are produced if the detaching rolls move abruptly. The Heilmann design is therefore not well-suited for high combing cycle frequencies, and therefore not for combers with high production rates.